Artificial and natural pollination of sunn hemp in Florida

Romy Krueger, Koon-Hui Wang, Robert McSorley, Raymond N. Gallaher

Abstract

Sunn hemp (Crotalaria juncea L.) is considered an important cover crop, providing benefits in weed, disease, and pest suppression, and supplying N to the soil. While the demand for sunn hemp seeds is high, seed production of sunn hemp in mainland US has been limited. Over the duration of two seasons (2005–06), various treatments for enhancing pod and seed set were tested in three experiments in northern Florida. The main objective was to determine if the plant growth regulator ethephon could substantially improve pod and seed set. Other methods tested were manual removal of the flower petals and beating of the stem to stimulate self-pollination within an inflorescence. In most instances, all treatments produced similar amounts of pods and seeds compared to an untreated control. In a few cases, significant (P < 0.05) differences among treatments occurred in pod and seed production, but these were very limited. In one trial in 2005, a higher ethephon concentration (16.7 μL·m–2 a.i.) produced more pods than a lower concentration (8.3 μL·m–2 a.i.), but did not produce more pods than the untreated control. Results suggest that native pollinators were competitive with the artificial pollination methods examined in this experiment.